The role of soil processes parameterization in numerical modelling of the atmosphere

A correct representation of the state of the soil, mainly in terms of temperature and moisture content, is getting more and more important
in state of the art numerical models for weather prediction and climate. The physical processes taking place in the soil and having an impact on
atmospheric dynamics will be described, together with their mechanisms of interaction with the atmospheric surface layer. The equations
decribing processes in the soil, in the form usually applied in numerical models of the atmosphere, will be presented along with their
typical discretization and their coupling with the numerical representation of the atmosphere and of other surface processes.
Finally, the most common techniques for defining the initial state of the soil for numerical weather prediction purposes will be introduced,
showing the advantages and drawbacks of each of them.